Q: I recently opened a 35-year-old red Bordeaux that has me confused. All was well until the second glass, when I noticed the flavor of old, wet newspaper, the telltale sign of TCA. But there was nothing on the nose to suggest cork taint. Can TCA manifest itself in flavor only? Or was this just the natural taste of this particular old wine?
A: Let me back up and explain TCA and cork taint for those not already acquainted. There’s a chemical compound called 2,4,6-trichloroanisole (TCA for short) that can make its way into wine. It’s not harmful, but it is super powerful and can impede our ability to smell and taste a wine's true aromas and flavors, leaving us with the impression of a wine that smells moldy or musty, like wet cardboard or newspaper.
TCA is caused by the intersection of chlorine and plant phenols, which are organic compounds. Because corks are made from the bark of an oak tree, TCA can originate there, but there are other places it can come from, like oak barrels or wood pallets or cardboard boxes. Tainted wines are often referred to as "corked," due to the not entirely correct conception that the cork is the source of the taint.
That musty smell is very distinctive, and it’s the first clue your wine might be tainted, but the only way to know for sure is with a lab test. There are lots of other reasons a wine might taste funky.
I think that it's also harder to pick out TCA in older wines, because as wines age their fruit flavors fade and more notes of earth, spice and leather emerge, which can make it more difficult to pinpoint a tainted element. Thresholds of perception for TCA vary broadly, but once I suspect a wine has it, I find it difficult to get any enjoyment out of it.